1. Field of the Invention
The present invention relates to a dielectric lens antenna and radio equipment including the same. More specifically, the present invention relates to a dielectric lens antenna for use in a motor-vehicle-mounted radar, and radio equipment including the same.
2. Description of the Related Art
With the recent development of motor-vehicle-mounted radar, a dielectric lens antenna for use in a motor-vehicle-mounted radar has been required to be resistant to influences due to snowfall and snow accumulation.
FIG. 8 shows a conventional dielectric lens antenna. FIG. 8A is a plan view; FIG. 8B is a sectional view taken along the line A--A of FIG. 8A.
In FIG. 8, a dielectric lens antenna 1 has such an arrangement that a lens 2, whose material is dielectric, is attached to a frame 3 for retaining it. Other components such as a primary radiator are omitted, since they are not the primary constituents in the present invention.
The dielectric lens antenna 1 having such an arrangement is mounted in such a manner that the z-axis direction shown in FIG. 8 is oriented toward a direction in which the motor vehicle is headed. As a result, snow accumulates on a surface of the lens 2 of the motor vehicle when it runs in snow, so that this leads to deterioration in the efficiency of the dielectric lens antenna 1.